U.S. patent number 5,159,168 [Application Number 07/667,021] was granted by the patent office on 1992-10-27 for sliding contact roller head.
This patent grant is currently assigned to Elpatronic AG. Invention is credited to Alfonso D'Aniello, Niklaus Portmann, Peter Taiana, Werner Urech.
United States Patent |
5,159,168 |
Portmann , et al. |
October 27, 1992 |
Sliding contact roller head
Abstract
A roller head (10) for a resistance seam welding machine has an
internally located sliding contact current transmission device (24)
between stator 12) and rotor (14) and is composed of a pair of
circular ring-shaped discs (26, 26') which extend radially between
rotor and stator, are fastened to the rotor on their outer
circumferences, carry axial sliding contact rings (32,32') on their
inner circumferences, and are flexible designed in their
intermediate parts (28,28') between inner and outer circumferences.
These sliding contact discs (26,26') are composed of a copper mesh,
to which the axial sliding contact rings (32,32') are fastened.
Thin-walled metallic diaphragms can also be used instead of the
copper mesh. The roller head (10) can transmit high welding
currents. As a result of the flexible design of the sliding contact
discs (26,26') the contact presssure, which is created by a stack
of plate springs (40), remains constant even with external
mechanical influences.
Inventors: |
Portmann; Niklaus (Bellikon,
CH), D'Aniello; Alfonso (Widen, CH),
Taiana; Peter (Staffelbach, CH), Urech; Werner
(Kaiserstuhl, CH) |
Assignee: |
Elpatronic AG (Zug,
CH)
|
Family
ID: |
4219316 |
Appl.
No.: |
07/667,021 |
Filed: |
March 7, 1991 |
Foreign Application Priority Data
|
|
|
|
|
May 29, 1990 [CH] |
|
|
01818/90 |
|
Current U.S.
Class: |
219/81; 219/84;
439/5 |
Current CPC
Class: |
B23K
11/3045 (20130101) |
Current International
Class: |
B23K
11/30 (20060101); B23K 011/06 () |
Field of
Search: |
;219/81,82,83,84,119,120
;439/3,5,18-23,29 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0182328 |
|
Oct 1989 |
|
EP |
|
636548 |
|
Jun 1983 |
|
CH |
|
610216 |
|
Jun 1978 |
|
SU |
|
Primary Examiner: Evans; Geoffrey S.
Attorney, Agent or Firm: McCormick, Paulding & Huber
Claims
We claim:
1. Roller head for a resistance seam welding machine, having a
stator assembly, an electrode roller which is rotatably mounted as
a rotor assembly on the stator assembly, a sliding contact current
transmission device which is arranged between the stator and rotor
assemblies and is pressed by spring force against at least one of
the assemblies and fluid ducts for passage of a coolant in the
stator assembly, rotor assembly and sliding contact current
transmission device, characterized in that the sliding contact
current transmission device comprises at least one circular disc,
which extends radially between the rotor and stator assemblies, has
a radially inner and a radially outer circumference and is flexibly
designed in its intermediate part between the inner and outer
circumferences.
2. Roller head as claimed in claim 1, characterized in that the
intermediate part is composed of a copper mesh.
3. Roller head as claimed in claim 1, characterized in that the
intermediate part is composed of a thin-walled metallic
diaphragm.
4. Roller head as claimed in claim 1, characterized in that the
intermediate part is provided with spokes.
5. Roller head as claimed in claim 4, characterized in that the
spokes are formed by slit-like slots in the intermediate part.
6. Roller head as claimed in claim 5, characterized in that the
spokes are designed as vanes for conveying the coolant.
7. Roller head as claimed in claim 3, characterized in that the
disc is formed on one of the stator and rotor assemblies.
8. Roller head as claimed in claim 1, characterized in that the
sliding contact current transmission device comprises two of the
circular discs, and the circular discs are axially spaced from each
other.
9. Roller head as claimed in claim 1, characterized in that the
disc is provided at least on one of the inner and outer
circumferences with a contact ring and is fastened at the other of
the inner and outer circumferences to one of the assemblies.
10. Roller head as claimed in claim 9, characterized in that the
disc is provided on the inner and outer circumferences with a
contact ring which is axially fastened to the intermediate
part.
11. Roller head as claimed in claim 9, characterized in that the
disc is provided on the inner and outer circumferences with a
contact ring which is set radially against the intermediate
part.
12. Roller head as claimed in claim 9, characterized in that for
the disc at least one contact ring is in axial sliding contact with
an annular contact surface of one of the
13. Roller head as claimed in claim 12, characterized in that the
contact ring is constructed from a material selected from the group
consisting of nickel silver, silver/graphite and
silver-plated/gold-plated copper and each associated annular
contact surface is constructed from a material selected from the
group consisting of copper and gold-plated copper.
14. Roller head as claimed in claim 12, characterized in that the
contact ring is composed of copper and each associated annular
contact surface is formed on an intermediate ring and constructed
from a material selected from the group consisting of nickel
silver, silver/graphite and silver-plated/gold-plated copper, which
is connected to one of the stator and rotor assemblies.
15. Roller head as claimed in claim 12, characterized in that a
spring device is arranged on that side of the contact ring which
faces away from the associated annular contact surface, in order to
produce a spring force applying contact pressure to the disc.
16. Roller head as claimed in claim 15, characterized in that the
spring device is comprised of a stack of plate springs.
17. Roller head as claimed in claim 1, characterized in that the
coolant is an emulsion containing oil, which serves as a lubricant
at the same time.
18. Roller head as claimed in claim 17, characterized in that the
emulsion is composed of 82% water, 15% rapeseed and 3%
emulsifier.
19. Roller head for a resistance seam welding machine, having a
stator assembly, an electrode roller which is rotatably mounted as
a rotor assembly on the stator assembly, a sliding contact current
transmission device which is arranged between the stator and rotor
assemblies and is pressed by spring force against at least one of
the assemblies and fluid ducts for passage of a coolant in the
stator assembly, rotor assembly and sliding contact current
transmission device, characterized in that the sliding contact
current transmission device comprises at least one circular disc,
which extends radially between the rotor and stator assemblies, has
a radially inner and a radially outer circumference and is flexibly
designed in its intermediate part between the inner and outer
circumferences, the disc is provided on at least one of the inner
and outer circumferences with a contact ring and is fastened at the
other of the inner and outer circumstances to one of the stator and
rotor assemblies, the contact ring is in axial sliding contact with
an annular contact surface of the other of the rotor and stator
assemblies; and the intermediate part of the disc is constructed
from a flexible material and serves as a pre-stressed spring in
order to produce a spring force and apply contact pressure to the
disc.
20. Roller head as claimed in claim 19, characterized in that the
current transmission device comprises two circular discs between
the stator and rotor assemblies; the stator assembly is designed as
a bipartite axle which is provided with two annular shoulders on
whose surfaces facing each other are arranged intermediate rings
constructed from a material selected from the group consisting of
nickel silver and silver/graphite which are in contact with the
contact rings of the two discs which are connected to the rotor
assembly.
21. Roller head as claimed in claim 19, characterized in that the
current transmission device comprises two circular discs between
the stator and rotor assemblies; the rotor assembly is designed to
be bipartite, and is provided with annular collars on whose
surfaces facing each other are arranged intermediate rings
constructed from a material selected from the group consisting of
nickel silver and silver/graphite which are in contact with the
contact rings of the two discs which are connected to the stator
assembly.
22. Roller head for a resistance seam welding machine, having a
stator assembly, an electrode roller which is rotatably mounted as
a rotor assembly on the stator assembly, a sliding contact current
transmission device which is arranged between the stator and rotor
assemblies and is pressed by spring force against at least one of
the assemblies and fluid ducts for passage of a coolant in the
stator assembly, rotor assembly and sliding contact current
transmission device, characterized in that the sliding contact
current transmission device comprises two circular discs, which
extend radially between the rotor and stator assemblies, each disc
has a radially inner and a radially outer circumference and is
flexibly designed in its intermediate part between the inner and
outer circumferences, each disc is also provided on at least one of
the inner and outer circumferences with a contact ring and is
fastened at the other of the inner and outer circumstances to one
of the stator and rotor assemblies, each contact ring is in axial
sliding contact with an annular contact surface of the other of the
stator and rotor assemblies, a spring device is arranged on that
side of each contact ring which faces away from the annular contact
surface in order to produce a spring force applying contact
pressure to the disc, the spring device includes a stack of spring
plates, and the stator assembly is designed as a bipartite axle
with two annular collars having surfaces facing each other as well
as the two contact rings on the discs, and the rotor is a single
part having an inner circumference with a flange to which the two
discs are fastened.
23. Roller head as claimed in claim 22, characterized in that the
surfaces of the two annular collars which face each other form the
annular contact surfaces of the stator assembly.
Description
BACKGROUND OF THE INVENTION
The invention relates to a roller head for a resistance seam
welding machine, having a stator, an electrode roller which is
rotatably mounted on the stator, a sliding contact current
transmission device which is arranged between stator and rotor and
is pressed by spring force against at least one of them, and ducts
in the stator, the rotor and the sliding contact current
transmission device for the passage of a coolant.
Such a roller head is known from U.S. Pat. No. 3,546,655 and from
U.S. Pat. No. 3,596,225.
Such roller heads with an internally situated sliding contact
current transmission device between stator and rotor could in fact
be envisaged as a substitute for the fluid roller heads which have
been used up to now, but practice has shown that they are not
suitable for this purpose in reality.
Fluid roller heads (CH-A-636 548, U.S. Pat. No. 4,188,523) are used
for welding inside narrow can bodies. Between the stator and the
rotor there is an annular gap in which there is a fluid metal, for
example, quicksilver or a gallium alloy, which serves to transmit
current from the stator to the rotor. As such roller heads require
careful sealing and constant checking of this sealing, and as the
fluid metals used are not particularly good heat conductors, and by
comparison with copper, are also not good electrical conductors,
and as, moreover, with the use of a gallium alloy, problems may
arise from the fact that this metal alloy solidifies at
temperatures lying not far below room temperature, such fluid
roller heads have already been replaced by a roller head with an
externally situated sliding contact current transmission device
(EP-B1-0 182 328). This known roller head, which has been developed
by the Applicant, does remove the aforementioned problems of fluid
roller heads, but requires a reconstruction of the welding arm of
the resistance seam welding machine if it is to be incorporated
instead of the fluid roller head which has otherwise been used in
the case of this machine.
The known sliding contact roller heads hereinbefore mentioned, in
view of the overall dimensions, can in fact be used instead of
fluid roller heads, but they are inferior to the fluid roller heads
in respect of the current transmission capacity and length of life,
because they have costly brush constructions as a sliding contact
current transmission device or as a constituent of the same. The
springs which are necessary for pressing the brushes on, also lead
to the following further disadvantage.
In the case of the roller head according to U.S. Pat. No.
3,546,655, there are provided on the stator two horizontal pins, on
which brush segments are arranged in the form of a ring and are
held together here by 0-shaped rings. The rotor carries convex
conductor parts between both brush rings. Between the convex
conductor parts and the rings of brushes are provided further
conductor parts which are constructed planar on their side facing
the rings of brushes and concave on the opposite side. Horizontally
arranged compression springs press the brush segments against the
further conductor parts and also the latter against the convex
conductor parts. With eccentricity or out-of-true running of the
rotor, the planar surfaces between the brush rings and the further
conductor parts can in fact move vertically relative to each other
and the further conductor parts can also perform curved movements
on the convex surfaces, but many components are involved in these
movements, and considering the high electric currents which have to
be transmitted in such roller heads between stator and rotor, all
current transmission surfaces moving against each other are
basically sources of loss which reduce the load-carrying capacity
of the roller heads.
Attempts have been made to remove these problems with the sliding
contact roller head according to U.S. Pat. No. 3,596,225, merely by
providing on the rotor a cylindrical inner surface with which all
the brushes which are provided on the stator are in sliding
contact. For this purpose, each brush is pressed against the rotor
by a radial compression spring, which is arranged centrally
underneath the brush. In this brush construction and also in the
brush construction of the sliding contact roller head according to
U.S. 3,546,655, the contact pressure between the brushes and the
contact surfaces of the rotor coordinated with the latter is
disadvantageously influenced by vibrations, for example, through
external shocks or through running out-of-true. The
current-carrying capacity is accordingly reduced. In other
respects, the sliding contact according to U.S. Pat. No. 3,596,225
has a plurality of brushes, all of which represent wear parts and
therefore make frequent maintenance necessary.
SUMMARY OF THE INVENTION
The object of the invention is to modify a roller head of the type
hereinbefore mentioned in such a way that in respect of overall
dimensions, current transmission capacity and length of life, it is
comparable with fluid roller heads which have been used up to now
and which it is intended to replace, and moreover, the sliding
contact current transmission device between the stator and rotor
has a contact pressure which remains practically uninfluenced by
vibrations, eccentricity etc.
This problem, originating from a roller head of the type
hereinbefore mentioned, is solved according to the invention in
that the sliding contact current transmission device is composed of
at least one circular disc, which extends radially between rotor
and stator and is flexibly designed in its web or intermediate part
which is placed between the inner and outer circumference.
In the roller head according to the invention, the welding current
is transmitted from the welding arm of the resistance seam welding
machine, through the stator which is clamped in the arm, through at
least one flexible sliding contact disc to the electrode roller. As
the sliding contact disc is flexible in its intermediate part, that
part can yield axially and radially in the event of eccentricity,
vibrations etc., so that the sliding contact circumferential area
of the disc, over which the current transmission occurs, remains
uninfluenced by such external mechanical influences, and for
practical purposes the contact pressure is therefore also not
disadvantageously influenced. Moreover, the roller head according
to the invention manages with a minimal number of components, which
considerably reduces the manufacturing costs, maintenance
expenditure and wear.
In one development of the invention the construction of the
intermediate part is particularly simple and makes a problem-free
transmission of very high welding currents possible.
In another development of the invention which provides for the
replacement of the copper mesh by a thin-walled metallic diaphragm,
it is possible to manufacture the disc as one part with the stator
or rotor.
In another development of the invention even with a greater
thickness of the disc, the mobility of its intermediate part in
axial direction is guaranteed by the design of the intermediate
part with spokes.
In another development of the invention an intense cooling of the
electrode roller and of the sliding contact surfaces is ensured by
the fact that the spokes designed as blades are brought into play
for conveying coolant. Here, it is sufficient to design only some
of the spokes as blades.
In the development of the invention the disc can in fact be formed
on the stator or rotor, for which the aforementioned development of
the roller head with a diaphragm as an intermediate part of the
disc is suitable, but the diaphragm can also readily be welded or
soldered to the stator or rotor.
One development of the invention is preferred, because it
distributes the current load of the sliding contact current
transmission device to two discs, and so makes smaller
cross-sections possible, and because the spring force for the
contact pressure can be created with simple measures, for example,
by a stack of plate springs arranged between the two discs, or
through the design of the discs themselves as flexible
diaphragms.
Other developments of the invention make possible the appropriate
selection of sliding contact rings used in the sliding contact
area. Thus, contact rings of nickel silver can be firmly connected
to a flexible copper mesh (for example, by electron beam welding),
which are mounted (welded) on the outer circumference, once again
in copper contact rings. Instead of nickel silver, a compound of
silver/graphite or even silver-plated or gold-plated copper can
also be used. If intermediate rings are used for working, copper
contact rings or silver-plated or gold-plated copper contact rings
can be welded or soldered to the flexible copper mesh, instead of
the silver contact rings, and the nickel silver or silver/graphite
or silver-plated/gold-plated copper contact rings are clamped to
the stator or rotor as inexpensive wear parts.
Still other developments of the invention represent preferred
specific embodiments with two sliding contact discs in each case.
If the intermediate parts are composed of copper mesh, a stack of
plate springs is, as already mentioned, suitably arranged between
two discs in order to create the spring force. If the intermediate
parts are manufactured as diaphragms composed of a flexible
material, and can for this reason be used at the same time as a
spring, the mutual spacing of the sliding contact surfaces of the
intermediate rings in the inserted position is smaller than the
spacing which the sliding contact surfaces of the axial sliding
contact rings have in the non-inserted position. Each diaphragm is
therefore in a position to create the spring force for the contact
pressure itself.
In a further development of the invention according to the cooling
of the roller head occurs through a special emulsion containing
oil, which not only intensely cools the sliding contact surfaces,
but lubricates them in addition. As compared with water that is
customary, such a coolant has the advantage that the contacts are
not contaminated by lime or other impurities. The emulsion used is
stable and above all, suitable for foodstuffs. The flow of coolant
through the disc(s) during cooling can be controlled in a simple
way by the position and the size of the slits which are provided in
the intermediate part in order to form the spokes.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplified embodiments of the invention are described in greater
detail hereafter by reference to the drawings.
FIG. 1 shows a first specific embodiment of a roller head according
to the invention,
FIG. 2 shows a second specific embodiment of the roller head
according to the invention,
FIG. 3 shows a third specific embodiment of the roller head
according to the invention,
FIG. 4 shows as a detail a view in the direction of an arrow IV in
FIG. 3,
FIG. 5 shows a diagrammatic partial view in order to illustrate a
fourth specific embodiment of the roller head according to the
invention,
FIG. 6 shows a diagrammatic partial view in order to illustrate a
fifth specific embodiment of the roller head according to the
invention, and
FIGS. 7a-7g show various designs of spoked diaphragms which can be
used in the roller head according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a sectional view of a first specific embodiment of a
roller head, indicated generally by the reference 10, for an
unillustrated resistance seam welding machine for resistance roller
seam welding of can bodies. The roller head 10, in the exemplified
embodiment illustrated, has a stator 12 designed as a bipartite
axle, on which stator a rotor 14 is rotatably mounted by means of
ball-bearings 16,16'. (Identical reference numbers provided with a
dash each indicate the other part of a pair of identically designed
parts). For this mounting, the roller head 10 has, in the manner
illustrated, outer bearing housings 18,18' fastened to the stator
12, and inner bearing housings 20,20' fastened to the rotor 14,
between which the ball-bearings 16,16' are arranged. The outer and
inner bearing housings 18,18' or 20,20' are composed of non-rusting
antimagnetic steel and consequently have low eddy current losses.
In all the exemplified embodiments illustrated, the outer rings of
ball-bearings are each electrically separated from the outer
bearing housing 18,18' by insulation 22,22'. Instead of or in
addition to this, the inner rings of ball-bearings can also be
separated from the inner bearing housing 20,20' by insulation (not
illustrated).
The stator 12 is clamped so that it conducts well electrically, to
the free end of a likewise unillustrated welding arm of the
resistance seam welding machine. The welding arm and the stator 12,
when the resistance seam welding machine is in operation, conduct
the welding current and for this reason (just as the rotor 14) are
composed of material which conducts electricity well, preferably
copper. This welding current has to be transmitted by the stator 12
to the rotor 14, which transmits it to the welding point,
preferably via an unillustrated electrode wire. For current
transmission between stator and rotor there is provided a sliding
contact current transmission device, which is indicated generally
by the reference 24 and in the exemplified embodiment illustrated
in FIG. 1 has two circular ring-shaped discs 26,26' which extend
radially between rotor and stator at a mutual axial spacing and are
flexibly designed in their intermediate parts 28,28' between the
inner and outer circumferences.
The two flexible sliding contact discs 26,26' are each composed of
a copper mesh, on which a contact ring 30,30' on the stay part
28,28' is axially fastened (e.g. welded) to the outer periphery of
the disc in each case, and an axial sliding contact ring 32,32' on
the intermediate part is axially fastened (e.g. electron
beam-welded to the inner periphery of the disc in each case. The
rotor 14 has on its inner circumference a flange 34, on which the
discs 26,26' are fastened by means of unillustrated screws or
merely by pressing, so that they conduct electricity well. Each
axial sliding contact ring 32,32' is in sliding contact with an
associated annular contact surface 36,36' of the stator 12. Each
half of the stator 12 is provided with an annular collar 38 or 38',
on which the annular contact surfaces 36 or 36' are formed. Between
the discs is provided a spring device in the form of a stack of
plate springs 40 for pressing the discs 26,26' against the stator
12. The plate springs create the necessary contact pressure between
the axial sliding contact rings 32,32' and the annular contact
surfaces 36,36' of the stator 12 which are associated with the
rings.
The inner space between the stator 12 and the rotor 14 is sealed by
means of O-shaped rings and shaft seals in the manner illustrated
in FIG. 1. As the rotor 14 and the sliding contact surfaces have to
be intensely cooled, ducts 52,52' and 53,53' are provided in the
stator 12, ducts 54 in the rotor 14, and ducts 55' in the flexible
sliding contact discs (ducts corresponding to the ducts 55', which
are provided in the disc 26, are not visible in FIG. 1) for
conducting a coolant through the roller head 10. Coolant is
introduced into the duct 52 when the resistance seam welding
machine is in operation and flows through the duct 53, through the
non-visible ducts of the disc 26, through the ducts 54,55' and
finally back through the ducts 53',52'.
A stable emulsion, and one which is above all suitable for
foodstuffs, is used as a coolant for cooling and simultaneous
lubrication, this being composed of 82% water, 15% rapeseed oil and
3% emulsifier. The emulsifier ML-55-F of Hefti AG, Zurich, has
proved to be particularly suitable. More precise details about this
emulsifier can be found in the Technical Data Sheet No. 3.201-d of
Hefti AG.
In order to manufacture the emulsion, the emulsifier, which can be
in the form of a concentrate, is added to water. Thereafter,
vigorous agitation with a stirring bar takes place, until the
emulsifier has completely dissolved in the water. The rapeseed oil
is now carefully mixed with this. Finally, the emulsion must be
mixed vigorously in a mixer and for a long time (at least 8
minutes), in order to obtain good stability in the emulsion. In
order to prolong the stability, the emulsion can, if necessary,
have a stabilizer mixed with it (as in the case of coolants and
lubricants of machine tools).
The temperature of the coolant when it enters the roller head must
reach 20.degree. to 25.degree. C., whereby the formation of
condensation water is completely prevented.
The aforedescribed sliding contact current-transmission device 24
between rotor and stator of the roller head makes radial and axial
relative movements possible between them without the contact
pressure being disadvantageously influenced thereby. The copper
mesh of the discs 26,26' ensures this relative mobility. The plate
spring assembly 40, on whose spring force this relative mobility
has no influence, keeps the contact pressure constant.
Possible alternatives to the sliding contact current-transmission
device 24 illustrated in FIG. 1 are now described hereafter with
reference to FIGS. 2 to 7.
FIG. 2 shows a second specific embodiment of the roller head 10, in
which each disc 66,66' on the inner and outer circumference is
provided with a contact ring 62,62' or 60,60', which is placed
radially against the intermediate part 68,68'. The inner contact
rings 62,62' once again form axial sliding contact rings which,
however, in contrast to those in FIG. 1, are not composed of nickel
silver or silver/graphite, but of copper, and are welded or
soldered to the flexible copper mesh which forms the intermediate
part 68,68' of the discs 66,66'. The associated annular contact
surfaces 36,36', which in the exemplified embodiment in FIG. 1 are
formed on the annular (ring) collars 38,38', are formed on
intermediate rings 64,64' of nickel silver or silver/graphite or
silver-plated/gold-plated copper, which are connected to the stator
12. The intermediate rings 64,64' are clamped to the stator 12 as
inexpensive wear parts. To this end, there is arranged between them
a clamping ring 65, which, when the stator 12 is assembled, presses
the intermediate rings 64,64' against two annular shoulders 69,69'
of the stator. In the exemplified embodiment according to FIG. 2
also, the contact rings 60,60' and the flange 34 are provided with
ducts (not illustrated) for conveying the coolant through. In other
respects, the construction of the roller head according to FIG. 2
corresponds to that according to FIG. 1 and for this reason does
not need to be further described.
The advantage of the embodiment according to FIG. 2 as compared
with that according to FIG. 1 can be seen in the fact that copper
contact rings can be better welded or soldered to the copper mesh,
and that intermediate rings of nickel silver or silver/graphite or
silver-plated/gold-plated copper which do not have to be soldered
or welded can be used, which, moreover, can be used on both sides.
On the boundary surface between the intermediate rings 64,64' and
the stator 12 contact transition points do in fact exist, but they
are stationary contact transition points, that is to say, they are
not sliding contact transition points, so that they do not cause
noticeable additional losses.
FIG. 3 shows a third specific embodiment of the roller head 10, in
which the copper mesh of the stay parts 68,68' in the specific
embodiment according to FIG. 2 has been replaced by thin-walled
metallic diaphragms 78,78' of the type illustrated in FIG. 4 or
FIG. 7. The arrangement of the intermediate rings 64,64' and of the
clamping ring 65 associated therewith corresponds to that shown in
FIG. 2 and for this reason does not need to be described again.
In the specific embodiment according to FIG. 3, the rotor 14 is
once again constructed as one part. The diaphragms 78,78' are
formed on the rotor 14, that is to say, manufactured as one part
therewith. The axial sliding contact rings 72,72' are formed on the
diaphragms 78,78'. This design with contact rings moulded on merely
serves to explain one exemplified embodiment, for it is readily
possible to manufacture the diaphragm 78,78' as separate parts and
to solder or weld them to the axial contact rings 72,72' and also
to the rotor 14. In the exemplified embodiment illustrated, rotor,
diaphragms and axial sliding contact rings have been machined from
the solid.
In order to ensure the relative mobility between the rotor 14 and
the stator 12 in axial direction, the diaphragms 78,78' are
provided with slits 79,79'. These slits have been cut hair-fine
into the diaphragms with a laser or by other suitable means. The
diaphragms 78,78' are additionally provided with holes 80,80' for
conveying the coolant through.
In the exemplified embodiment according to FIG. 3, the diaphragms
78,78' (just as the rotor 14 and the axial sliding contact rings
72,72') are composed of a flexible material and can therefore be
used as a spring at the same time. The stack of plate springs 40
therefore becomes superfluous. In order to create the spring
pressure force of the discs, the spacings between the contact
surfaces of the axial sliding contact rings 72,72' and the
clearance width between the intermediate rings 64,64' are so
selected that in the inserted position, each diaphragm is
prestressed as a spring, and thus creates the necessary contact
pressure itself. Through the position of the slits 79,79' in the
diaphragms 78,78', the spring constants and the thickness of the
diaphragms can be matched to a great extent. A
copper-cobalt-beryllium alloy can be considered as the material for
their manufacture. If required, the spring properties can be
improved by increasing the beryllium content of the alloy, but with
this may be associated a deterioration of the electrical
conductivity.
The throughflow of the coolant can be controlled by suitable design
of the slits, and more especially, the holes 80,80'.
A special advantage of the specific embodiment according to FIG. 3
consists of the fact that the rotor 14 with moulded-on diaphragms
78,78' and axial sliding contact rings 72,72' can easily be
replaced as a wear part. The intermediate rings 64,64', when worn,
then merely have to be turned around. This specific embodiment is
distinguished by a minimum number of components and by a clear
division of wear parts and parts which can be re-used.
FIGS. 5 and 6 show variants of the specific embodiment according to
FIG. 3. In the specific embodiment of the roller head according to
FIG. 5, the discs 86,86' are designed in the form of diaphragms
88,88' with axial sliding contact rings 82,82' as separate parts
and fastened to the flange 34 of the rotor 14, for example, by
means of screws (schematically illustrated). The axial sliding
contact rings 82,82' butt against intermediate rings 84,84'. In
other respects, this specific embodiment corresponds to that
according to FIGS. 3 and 4, and for this reason does not need to be
further described.
In the specific embodiment of the roller head according to FIG. 6,
the stator 12 is designed as one part and the rotor 14 as two
parts, and therefore the reverse of FIG. 3. Also, in contrast to
FIG. 3, the discs 96,96' with their diaphragms 98,98' are formed
not on the rotor 14, but on the stator 12, and the intermediate
rings 94,94' and their clamping ring 93 are provided on the rotor
14 instead of on the stator 12, as illustrated in FIG. 6. The axial
sliding contact rings 92,92' formed on the diaphragms 98,98' butt
against the intermediate rings 94,94', which for their part, are
supported against ring collars 95,95' of the rotor 14. Otherwise,
the specific embodiment according to FIG. 6 corresponds to that
according to FIGS. 3 and 4, and therefore likewise does not need to
be described in greater detail. The friction occurring in the
embodiment according to FIG. 6 would appear to be somewhat greater
than in that according to FIGS. 3 and 4.
As a result of the provision of the slots 79,79' in the diaphragms
78,78' according to FIG. 4, spokes are formed between the slots,
and the diaphragms are thus converted into so-called spoked
diaphragms. FIG. 7 shows various alternative specific embodiments
of such spoked diaphragms.
FIG. 7a and 7b show two types of slit-like slots 99a or 99b in the
diaphragms. FIGS. 7c-7g show various cross-sectional views of
spoked diaphragms of the type illustrated in FIGS. 7a and 7b. The
slit-like slots 99a,99b can be cut by means of a laser. According
to FIG. 7e, the axial sliding contact ring E provided on the inner
circumference can be a moulded-on part of the diaphragm. According
to FIGS. 7c and 7d, the axial sliding contact ring C or D is in
each case a ring which is mounted on the diaphragm and is joined
thereto. According to FIGS. 7f and 7g, such an axial sliding
contact ring F or G can be soldered to the inner circumference of
the diaphragm or connected to the same by sintering.
The variants of design according to FIG. 7 moreover show that the
spokes can be designed in the manner of shovel-blade vanes S for
conveying the coolant, as is indicated more especially in FIGS.
7c-7e.
With reference to the drawings, only specific embodiments in which
the sliding contact current transmission device 24 has two discs
have actually been described heretofore, but specific embodiments
with one disc in each case are also possible. It is merely a
question of the available space and the available transmission
cross-sections. In the specific embodiment according to FIG. 1, a
type of plate spring or a stack of springs could be fastened to the
flange 34 instead of the second disc, in this case, which ensures
the necessary contact pressure of the disc against the contact
surface 36 or 36'. The same would apply to the specific embodiment
according to FIG. 2. In the specific embodiments according to FIGS.
3-7, the creation of the spring force would require no additional
spring device, because in these specific embodiments each disc is
itself designed as a spring in any case.
If, in the case of the specific embodiments according to FIGS. 3 to
7, the diaphragms themselves are not designed as springs, a stack
of plate springs such as the stack of springs 40 shown in FIGS. 1
and 2, can be provided to produce the spring force which is
necessary for the contact pressure.
* * * * *